In as much as all CCNA topics are to be covered before the exams, there are certain topics that requires more attention and time, VLAN, EIGRP, IPV6 address, DHCP, PPPOE, IPSEC, BGP, CISCO DNA etc. We will talk about them detaily in subsequent paragraphs. VLAN VLAN is any broadcast doamin that is partitioned and isolated in a computer network at the data link layer. VLANs make it easy for network admins to partition a single switched network to match the functional and security requirements of their systems without having to run new cables or make major changes in their current network infrastructure. VLANs are of different types, Default VLAN, Data VLAN, Voice VLAN, subnetting practice Management VLAN, and Native VLAN. We cannot talk about VLANs and not mention Collision domains and broadcast domains. A collision Domain is a network segment connected by shared medium or through repeaters where simultaneous data transmissions collide with one another. Collision domain